1. Field of Invention
This invention pertains to a mounting device for a rotary encoder, and more particularly to a mechanical interface between a rotating apparatus such as an electric motor and the like, and an electronic device used for accurately monitoring rotation.
2. Description of the Prior Art
It is frequently necessary to monitor the rotation of various equipment such as electric motors, generators, and so forth. It has been found that this monitoring is best accomplished by providing an electronic device known as an encoder which is mechanically coupled to a rotating shaft of the monitored device and which senses the angular movement of the shaft. Usually the encoder is mounted on the monitored equipment by a solid metallic mounting member having either a tubular or square shape with a central opening. A flexible coupling disposed in the central opening is used to connect the shaft to the encoder.
A by-product of rotational equipment especially if the equipment has a large power output, is the production of intense spurious electro-magnetic fields (or EMF). Additional ground current loops are also formed, especially if the equipment constitutes or includes induction or brushless AC/DC motors. Equipment including AC/DC motors with brushes may also produce high frequency noise signals. These spurious signals are readily transmitted to the encoder through the mounting member. However, since the encoder utilizes digital electronic circuits, it is particularly susceptible to spurious signals because they may cause the encoder to malfunction and burn out.
In addition, the monitored equipment frequently is operating at elevated temperatures. For example, some electric motors may be operating at over 100.degree. C. However, the digital circuitry of the encoder has a lower operating temperature range. As a result, heat is transmitted to the encoder through the mounting member which may also cause it to malfunction.
Thus, there is a need for a novel mounting means for mounting an encoder to the rotating member of an apparatus, which mounting means holds the encoder firmly and securely and at the same time protects the encoder from undesirable electrical signals or heat from the monitored apparatus.